When a television stops working correctly, the symptoms can feel random or confusing. A TV that shows no power, a screen that stays black, or a picture full of lines often leaves people guessing which internal component is to blame. At TVpartsToday, we encourage a more strategic approach called symptom mapping. This method allows you to read the signals your TV is giving you and trace them to the part that needs replacement. It reduces guesswork, prevents ordering the wrong component, and makes DIY repair far more affordable and predictable.
Rather watch a video? Check out our helpful YouTube video on Troubleshooting 101 below:
When the TV Will Not Power On or Turns Off Randomly
A television that refuses to start or loses power intermittently is usually dealing with a failure in either the power supply board or the main board. The power supply is responsible for converting incoming electricity into the voltages required by the rest of the system. When it falters, the TV may not respond to the power button at all. If the standby light still illuminates but the set will not turn on fully, the main board may not be sending the necessary command to activate the TV.
Physical inspection can provide useful clues. Burn marks, swollen components, or blown capacitors on the power supply are strong indicators of failure. For those comfortable with advanced testing, verifying standby voltage and output voltage with a multimeter can confirm the diagnosis.
Rather watch a video on the topic? Check out our YouTube video below:
When the TV Turns On but the Screen Stays Completely Black
A black screen does not always mean the TV is dead. One of the most important diagnostic steps is listening for audio and testing the screen with a flashlight. If you shine a light at an angle and see a faint image, the picture is still being produced internally. This points to a problem with the backlight system, the LED driver, or the power supply output to the backlights. If no image or sound is present at all, the main board becomes a stronger suspect.
The flashlight test helps determine whether the issue affects the display itself or the illumination behind it. Backlight failures are among the most common issues in LED televisions and are often repairable with replacement LED strips or an LED driver board.
Unsure about the flashlight test? Check out our video on the topic below:
When the Picture Shows Discoloration or Unusual Tints
Incorrect colors, tinted images, or distorted shading usually originate from the T Con board or from the video processing section of the main board. The T Con board translates video information into pixel level timing, so any irregularity in that conversion can produce washed out colors or strange hues. If the tint appears specifically blue, the backlight phosphors may be deteriorating, which is a separate issue related to the LED strips rather than the T Con itself.
For sets where audio, menus, and system functions still behave normally, a T Con issue is more likely than a main board problem. Sharing a photo of your screen with us can help confirm the diagnosis quickly. Also, check out our Blue Screen vs Blue Tint blog article for more information!
Still struggling? Check out our helpful video below:
When Only Part of the Screen Displays an Image
A half screen image, partial picture, or split display almost always points to a T Con failure. These boards can malfunction in ways that prevent one side of the panel from receiving the correct signal. Some T Con boards are separate components, while others are integrated directly into the main board, particularly on more compact or budget models. If you open your TV and do not see a standalone T Con, it is likely built into the main board.
Rather watch a video? Check out the repair video below:
When the Screen Flickers or Shows Lines Across the Display
Lines, flickering, or banding on the screen occur when the timing between the main board, T Con board, and panel becomes disrupted. If the lines stay fixed in place, the panel may be damaged. If they move, flicker, or change appearance, the T Con board is usually responsible. Ribbon cables that connect these boards can become loose, and reseating them should always be part of the diagnostic process. While ribbon cables rarely fail outright, a poor connection can mimic board failure.
Still need some more information? Check out our blog article on Horizontal vs. Vertical Lines!
When Inputs or HDMI Ports Stop Working
If the TV powers on normally but does not detect devices on any of the HDMI ports, the issue almost always resides in the main board. This board controls all inputs, interprets HDMI signals, and manages system communication. Before replacing anything, test various input devices and cables. If multiple inputs fail consistently, the main board is the correct component to focus on.
We've got a video for this one too! Check it out below:
Why Correct Part Numbers Matter in Every Repair
Identifying the right replacement part requires careful attention to part numbers. Manufacturers print board numbers directly onto the circuit board, but these numbers refer only to the design layout and not to the specific programmed or configured version you need. The correct identifier is the part number, found on the barcode label. Matching part numbers ensures the replacement board is fully compatible with your TV’s firmware and internal architecture.
TVpartsToday can assist with this step. Sending us a clear photo of your board allows us to verify the correct replacement so you can complete your repair with confidence.
Symptom mapping transforms TV repair from guesswork into a targeted process. By learning how specific failures point to specific components, you can identify the right part, avoid unnecessary purchases, and complete repairs effectively. Whether you need a main board, power supply, T Con board, LED driver, or backlight strips, TVpartsToday is here to help you diagnose accurately and select the correct part number for your TV model.
Need Help?
If you’re still unsure about the issue or need to replace a part, reach out to TVpartsToday. We can help you identify the exact cause of the problem and provide the right replacement part!
Would you rather watch a video? Check out our helpful Troubleshooting 101 playlist over on YouTube!
Would you rather chat with a seasoned repair expert? Head on over to our TVRepairHelp subReddit!
Need help finding the right board or part?
Call us at 930-212-1975 or browse our inventory online.
DIY-friendly parts, fast shipping, and expert support – only at TVpartsToday.